Heat is commonly called the "silent killer," but a new map speaks volumes about the parts of our country that have experienced a significant rise in dangerous summer heat. Some notable hotspots include Los Angeles and New York.

What's happening?

One climate scientist's analysis of the increase in heat during the summer over the past nearly 130 years shows which parts of the United States are experiencing the biggest spikes in summer heat, The Guardian reported. Brian Brettschneider studied federal data that dates back to 1895. 

His findings show that 117 million people, over a third of those who live in the U.S., are in a county where the summer is now at least 2.7 degrees Fahrenheit hotter than it was in 1895. Over 55 million people live in counties with summer temperatures hotter by 3.6 degrees or more.

Some of the country's largest cities are among the hotspots, Brettschneider found. Counties that include Phoenix and Los Angeles are enduring summers now 4 degrees warmer than the 1895 average. 

New York City's summer is 3.8 degrees hotter. Most of the country, particularly its western half, is experiencing hotter summers compared to how hot they were on average 129 years ago.

Why are more scorching summers important?

Heat is the leading weather-related cause of death in the U.S. Last year was the country's hottest summer on record, and this summer has been a scorcher, too. 

More than 100 million people have been under heat alerts for various heat waves this summer, as ABC News has reported. Maricopa County in Arizona confirmed 27 heat-related deaths this year through the third week of July, with another 396 deaths under investigation.

Studies show that hotter summers also worsen droughts as they become more frequent and intense and last longer. The increasing heat also stretches the wildfire season, as rising aridity dries out forests.

"We are now starting to have this complicated relationship with summer," said Deepti Singh, founder of the Climate Extreme Labs at Washington State University, per The Guardian. "The extreme events are happening more quickly than the rate of mean temperature warming, which is putting a strain on everything we depend upon as a society. If you talk to climate scientists, there's certainly an anxiety as summer approaches. It can be distressing."

What's being done about hotter summers?

Doing things to help cool our planet is crucial to making summers safer. We can all make lifestyle choices to help reduce pollution that raises our planet's temperature. This can include investing in clean energy sources, cooking our food differently, and even using smart home technology.

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